P-0102 - Qualitative analysis of the employment of brachytherapy in neoadjuvant therapy of liver cancer
|Date||28 June 2014|
|Event||World GI 2014|
|Topics|| Hepatobiliary Cancers
Surgery and/or Radiotherapy of Cancer
|Citation||Annals of Oncology (2014) 25 (suppl_2): ii14-ii104. 10.1093/annonc/mdu165|
S. Yoshida, I. Pereira de Oliveira, T. Figueiredo
Hepatocellular carcinoma (HCC) is an aggressive tumor, to which surgery is the main option of treatment. However, as many patients present large tumors or underlying liver dysfunction, nonsurgical therapy – percutaneous ethanol injection, radiofrequency ablation, transarterial chemoembolization, radiotherapy and systemic therapy – is often used. Another form of non-surgical therapy is brachytherapy, but, secondary to the shortage of studies regarding its effects on normal liver tissue, it is not yet widely used for HCC. In this modality of treatment, which can be independent or combined to other therapies, radioactive seeds are inserted in intimate contact with the region to be treated, sparing the healthy surrounding tissue and, therefore, minimizing the risks of side effects. This allows physicians to reach a high level of dose conformity. The presently existing brachytherapy implants use metallic seeds of titanium and iodine-125 as radioactive source. This model is not ideal, because it is nonabsorbable and causes fibrosing reaction at the level of the implant. Besides, this source emits low energy gamma waves, with high penetration, for long period of time, which increases the exposure over healthy tissues. Sm-153 ceramic seeds represent an alternative proposition of brachytherapy implants, with the aim of minimizing the deleterious effects of the seeds commonly used. In order to analyse the brachytherapy as an option for patients undergoing HCC and to compare the Sm-153 to other radioactive elements, a qualitative analysis of articles is proposed.
Researches through articles published on Scielo, UpToDate and PubMed platforms.
The number of articles that report brachytherapy as a neoadjuvant therapy for HCC is scarce, despite the fact that this modality of treatment is widely used in many other types of tumors. The studies have shown satisfactory therapeutic efficacy when brachytherapy is compared to other types of nonsurgical treatment. Sm-153 ceramic seeds presented characteristics that turned them into considerable options to the ones currently used. According to tests in vivo, they showed significant insolubility in body fluid, which keeps the radioactive material restricted to the implant region. Furthermore, they presented low inflammatory reaction and a considerable capacity of being reabsorbed (which was tested in vitro). As for its radioactive feature, also tested in vitro, the energy of the beta particle emitted by Sm-153 is enough to induce the death of tumor cells.
Although surgical treatment remains as the primary option for HCC, brachytherapy could be considered as a plausible future option, due to the smaller number of unfavorable results and to its good performance in the treatment of other types of tumor. Ceramic seeds with Sm-153 seem to be appropriate for its use in brachytherapy. The material is biocompatible, considerably bioabsorbable and the radioactive source releases effective dose for the control of tumor cells in vitro, which allows this particle to be manipulated within the standards of radioprotection.